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Stryofoam an OK replacement for Vapor Shield?


burgertech's Avatar
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01-27-05, 07:52 AM   #1  
burgertech
Stryofoam an OK replacement for Vapor Shield?

Hello all.

I live in Tampa, FL - very humind and tons of rain in the summer.

I had some warping of floor boards in my new home, directly under the windows in my kitchen, due to water leak. When we pulled the drywall away to find the source of the leak, we pulled away "Vapor Shield", the foil insulation product by FiFoil (www.fifoil.com).

I asked the warranty tech (from my homebuilder) doing the work if he was going to replace the Vapor Shield when they re-drywalled, and his answer was "no...we're going to use styrofoam between the firring strips to close the air gap." He claimed it has the same effetiveness.

He also claimed that the reason they were going to use styro was becuase Home Depot charges too much for the Vapor Shield!

My question is, am I being cheated? Is styrofoam a viable alternative?

Thanks so much for the help!

 
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resercon's Avatar
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01-27-05, 04:46 PM   #2  
Get yourself another contractor.

Is he paying for the vapor shield or are you? Since you are paying for the job, you are paying for the vapor shield. Styrofoam and Vapor Shield have different "Perm Ratings". And even though the Styrofoam may have a very low Perm Rating" it is still not as low as the Vapor Shield. This makes the styrofoam the path of least resistence for high humidity to permeate the structure, regardless of its low Perm Rating.

If you want to know more about Perm Ratings you can search the web for it or go to the site below. It discusses Perm Ratings, Thermal Moisture Dynamics and situations like your climate.

http://www.eere.energy.gov/consumeri...heets/bd4.html

 
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01-31-05, 10:00 AM   #3  
burgertech
The builder is paying - my home is still under the initial 1 year warranty (I built the home).

It would seem to me that, if Styro was just as good and cheaper, they would have used it in the first place.

I just want to make sure I'm not getting the short end of the stick here because they want to save $$$$.

If they insist on using styro, how can I make sure that it is comparable to the Vapor Shield?

Thanks so much for your help!

 
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01-31-05, 10:28 AM   #4  
The Vapor Shield must have a Perm Rating of 1 or less and probably around 0.01. I can assure you the styrofoam does not come anywhere near that rating. This is what you ask him to compare. You can contact the manufacturers on both both products and they should have specifications sheets on their products. I can assure you that the styrofoam does not qualify as a vapor barrier.

 
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